Elevator control



c. STANSBURY El AL ELEVATOR CONTROL Dec. 5, 1933.

Filed May 21, 1931 2 Sheets-Sheet l.

5 mwm D 1933- c. STANSBURY E1" AL 1,937,798

' ELEVATOR CONTROL Filed Kay 21'. 19:51 2 Smio'bs-Sheet '2 Patented Dec.5, 1933 UNITED STATES PATENT OFFICE 1,937,798 ELEVATOR CONTROL ofDelaware Application May 21, 1931. Serial 13 Claims.

.This invention relates to electronic control means which isparticularly advantageous for elevator control although not limited tosuch application.

An object of the invention is to provide for elevator control and otheruses electronic means for introducing a definite time interval betweensuccessive operations of a controlled translating device such forexample as the driving motor of an elevator.

Another object is to provide an improved elevator control systemincluding phase failure and phase reversal protection and protectionagainst premature starting of the elevator after stoppage thereof toafford passengers suflicient time to enter and leave the elevator.

Another object is to provide means for controlling the current flowthrough a gaseous electron tube in such a manner that after it has beenstopped, it is prevented from immediately starting again uponre-establishment of circuit connections by a negative grid potentialwhich is made to persist for a given time.

Another object is to provide means for introducing a definite minimumtime interval between successive operating periods of an electron tube,and means to eliminate such time interval at will.

Another object is to provide in an alternating current system forcombined phase failure and phase reversal protection, including meansfor introducing a time delay in the current flow upon re-establishmentof current supply after interruption thereof.

Other objects and appear.

The accompanying drawings illustrate an embodiment of the invention. Inthe drawings Figure l is an elementary diagram illustrating use of theinvention to delay the re-establishment of current flow through agaseous electron tube for a given time after interruption thereof.

Fig. 2 shows the application of the system illustrated in Fig. 1 incombination with a phase failure and phase reversal protective systemfor a three-phase circuit, while Fig. 3 illustratesthe system of Fig. 2as applied to an elevator driven by a polyphase motor and providing forphase failure, phase reversal and non-interference protection.

Referring to Fig. 1, L and I. are respectively the positive and negativelines of a direct current supply system, 1 is a gaseous electron tubehaving a cathode 2, an-anode 3 and a grid 4.

advantages will hereinafter An electromagnetic switch 5 is provided withan energizing winding 6, normally open main contacts '7, normally closedauxiliary contacts 8 and normally open auxiliary contacts 9. The systemalso includes a condenser 10 having plates of opposite polarity 11 and12. In circuit with the plate 12 and one of the contacts 8 may be aresistance 13, while another resistance 14 is connected between plate 11and the other of said contacts 8, which latter is also connected througha resistance 15 to the grid 4. A translating device 16, the current ofwhich is to be controlled, is connected between the cathode 2 and one ofthe normally open contacts 7, while the other of said contacts isconnected to line L The winding 6 is connected in series with a normallyopen push button switch 17 between the line L and the cathode 2, thelatter also being connected to the condenser plate 11, while the anode 3is connected to line L The system illustrated in Fig. 1 functions in thefollowing manner:

When the lines are deenergized, the grid 4 is substantially at thepotential of the cathode 2. With the lines energized and the push button17 depressed, circuit is closed from the line L to anode 3, cathode 2,push button 17, coil 6, to line L. The switch 5 is thus energized,thereby opening contacts 8 and closing contacts 7 and 9. Closure ofcontacts '7 connects the translating device in series with the tube 1,thereby supplying current to the former, while closure of contact 9impresses upon the plate 12 of the condenser the potential of line L,which is negative with respect to the cathode 2 by an amount, which isthe difference of the potential of lines L and I. and the voltage dropin the tube 1. The plate 11 of the condenser accumulates a correspondingpositive charge. If now the push button switch 17 is released, themagnet switch 5 is deenergized, thereby opening contacts 7 and 9 andclosing contacts 8. The current flowing through the translating device16 through contact '1 is thus interrupted and the charge of thecondenser 10 is terminated by the opening of the contacts 9. Thesimultaneous closing of contacts 8 connects condenser plate 12 to thegrid 4 and thus impresses thereon a potential negative with respect tothe cathode, while simultaneously a discharge circuit is completed fromcondenser plate 11 through resistance 14, contacts 8, resistance 13 toplate 12. v The negative charge of the condenser plate 12 is thusgradually reduced by the discharge current, until ultimately the gridagain reaches a potential which will permit current flow through thetube 1 if the push button 17 is depressed. The time when this takesplace depends upon the impedance of the resistances 13 and 14.Therefore, if the push button switch 1''! is tiepressed prematurely, thegrid has still a negative potential sufflcient to prevent current flowthrough the tube 1 and current supply to the translating device 16cannot be re-established until the negative potential of condenser plate12 and of the grid has been sufllciently lowered.

The system illustrated in Fig. 1 may also be used when the supply ofcurrent is alternating. In this case, the operation is substantially thesame as described heretofore except that current flows through the tube1, the electromagnetic winding 6 and the translating device 16 onlyduring alternate half cycles when the cathode 2 and line L are negativewith respect to anode 3 and line L Also the charging of condenser 10proceeds only during alternate half cycles when the cathode 2 isnegative with respect to anode 3. In order to avoid the completedischarge of the condenser 10 during alternate half cycles, in case ofalternating current supply, there is provided in series with the plate12, the resistance 13 which assures that only part of the chargeimpressed upon the condenser 10 during one of the charging half cyclesis again discharged during the alternate half cycle.

In order to smooth out the current fluctuations due to the alternatingvoltage in the coil 6 and translating device 16, it may be desirable insome cases to connect a rectifier 18 between the cathode 2 and the lineL. This rectifier may be of any well known type and. its effect insmoothing out the current supply to any translating device in serieswith the tube 1 is well known to those skilled in the art.

Fig. 2 shows the application of the system of Fig. 1 in combination witha phase failure and phase reversal protective system for a polyphasecircuit such as described in the application by Carroll Stansbury andGlendon C. Brown, Serial No. 432,278, filed February 28, 1930. However,the invention may be used in combination with other phase failure andphase reversal protective systems. In the system which is disclosed inthe aforementioned application, the current supply to a translatingdevice is controlled by an electron tube and conduction through thelatter is dependent upon normal conditions of voltages and phaserelation of the supply. To apply the present invention to such a system,the grid of the electron tube is infiuenced by the time delay featureinvolved in the present invention, so that in addition to preventingcurrent flow through the tube when conditions of current supply areabnormal, the tube is also prevented from re-establishment of currentflow to the translating device for a given interval after interruptionof such flow by the regular control instrumentalities.

Besides the elements of Fig. 1 which are indicated by like numerals inFig. 2, the latter has additional elements which are described in thefollowing: Three supply lines L, L and L supply polyphase current ofsuitable voltage. Connected between the lines L and L is a primarywinding 23 of a transformer having a secondary winding 24. The winding23 is provided with a mid-tap between which and the line L is connectedthe primary winding 21 of a second transformer 20, having a secondarywinding 22. The

system further includes a normally open triple contact push buttonswitch 19. Two of the contacts of the latter are respectively connectedin parallel with the two contacts of push button switch 17, while thethird contact of push button switch 19 is connected to one of thecontacts 8 which connects to resistance 15. It will be observed thatwith respect to the current supplied for the winding 6 and thetranslating device 16, the center tap corresponds to the line L of Fig.l. The grid 4 is connected in series with windings 24 and 22 and throughthe resistance 15 to one of the normally closed auxiliary contacts 8.All other connections are similar to those of Fig. 1.

In case of phase failure or phase reversal, the voltage impressed uponthe grid 4 is of such value and has such phase relation with respect tothe voltage impressed upon the main electrodes 2 and 3, as to preventcurrent flow through the tube and it therefore prevents current flow tothe electromagnetic switch 5 and the translating device 16. Thefunctioning of this part of the system is fully described in theabove-mentioned co-pending application. Thus, upon abnormal conditionsobtaining in the current supply, no current can flow through winding 6of the electromagnetic switch 5 and therefore no current can be suppliedto the translating device 16.

However, when normal conditions exist in the system and the push buttonswitch 17 is depressed the coil 6 is energized so that theelectromagnetic switch 5 closes the circuit of the translating device 16and current is supplied thereto in the manner already described. At thesame time the condenser 10 is charged in the aforedescribed manner andupon release of the push button switch 17 a negative potential isimpressed upon the grid 4 which prevents reestablishment of current flowthrough the tube upon reclosure of the push button switch 17 until thecondenser has been discharged as has been explained.

Push button switch 19 is provided to eliminate, when depressed, the timedelay effect of the condenser 10 upon the current flow in the tube 1. Itwill be noted that upon closure of switch 19, a circuit is completedfrom condenser plate 11 through said switch, through contacts 8 andresistance 13 to condenser plate 12 and another circuit is closed fromcathode 2, through switch 19, resistance 15, windings 22 and 24, to grid4. Thus the grid potential at the moment of depression of the button 19is determined solely by the drop in resistance 15 and the voltagesinduced in the windings 22 and 24 and if the conditions of currentsupply are normal, the tube will immediately conduct current, thuspermitting energization of winding 6 and current supply to thetranslating device 16. It is thus apparent that by the selective use ofpush button switches 19 and 17 current supply to the translating device16 and the winding 6 of the electromagnetic switch is controlled torespond either immediately or after a given time delay from the momentof previous interruption upon the depression of the respective button,the current supply being further responsive at all times to conditionsof voltage, phase rotation and phase continuity of the source of supply.

Referring now to Fig. 3, the system comprises the polyphase supply linesL L and L to which are connected in the aforedescribed manner, anelectron tube 1, transformer primaries 21 and 23 having respectivelysecondary windings 22 and 24, and a rectifier 18. The electron tube 1supplies rectified current for the various control instrumentalities ofthe system. An alternating current motor 25 operates an elevator cage26. The current through the motor is controlled by a pair ofelectromagnetic reversing switches 27 and 28, having normally open maincontacts 27' and 27 and 28 and 28" respectively, and normally openauxiliary contacts 27 and 28 respectively. Geared or otherwise connectedto the motor is a commutator 29 having rotating segments 29' and 29" andstationary contacts 29 to 29', inclusive, which stationary contactsengage one or the other segment as the motor rotates and the elevatorcar occupies various positions in the hatchway. An electromagnetic relay30 has a winding 30, normally open contacts 30" and normally closedcontacts 30, these latter contacts corresponding respectively to thecontacts 9 and 8 of Fig, 2. Mounted in the elevator cage are push buttonswitches 31, 32 and 33 corresponding to the three floors of the elevatorhatchway.

These push button switches have respectively.

normally closed contacts 31'', 32 and 33 and normally open triplecontacts 31', 32 and 33. Mounted on the floors adjacent to the hatchwaydoors are'the push buttons 34, and 36, one on each floor,-these pushbuttons having normally closed contacts 34 and 35 and normally opencontacts 34', 35 and 36". At each landing door are also mounted thenormally open hatchway switches 37, 38 and 39, these switches beingclosed when the hatchway door is closed. A similar switch 40 isconnected to the door of the elevator cage, and a normally closed stop.

button 41 is also mounted on the inside of the elevator cage. Theswitches 37 to 41, inclusive, are all connected in series and in serieswith the magnet coils of the switches 27, 28, so as to preventenergization of the latter if any one of them should be opened.

For the several floors are provided relays 42, 43 and 44, respectively,having magnet windings 42, 43 and 44, respectively and two pair ofnormally open contacts 42, 42; 43, 43; 44" and 44, respectively.

The system operates as follows: Assuming that the elevator is at thesecond floor and a passenger has entered and wishes to proceed to thethird floor, he closes the elevator door. thereby closing switch 40 andpushes button 31. This closes circuit from line L through tube 1 andfrom cathode 2 thereof over the normally closed contacts of push buttons33 and 32 to the center contact of normally open contacts of push button31, through winding 42 over switches 40, 41, 37, 38 and 39 to line L,and if the grid 4 does not have too high a negative potential withrespect to the cathode 2, tube 1 becomes conducting and relay 42 isenergized, thereby closing its normally open contacts 42 and 42. Closureof contact 42 closes a circuit from cathode 2 through contact 42 tocontact 29, over segment 29 to contact 29, through the coil of magnetswitch 27, through contacts 40, 41, 37, 38 and 39 to line L. Switch 27is thereby energized and this closes the circuit to the motor. Closureof contact 27 also completes a circuit from cathode 2 to contact 42through coil 42* through contacts 40, 41, 3'7, 38 and 39 to line L. Therelay 42 will thus remain closed if the push button 31 is released andit will also keep closed the electromagnetic switch 27 and maintain themotor energized and cause the elevator to rise to the third floor.

When the third floor is reached, contact 29 breaks with the segment 29".This opens the current supply to the switch 27 and disconnects themotor. In opening, switch 27 opens contact 27 thereby opening the supplyof current to the coil 42 and causing the relay 42 to open. If duringthe travel of the elevator, the stop button 41 should be pressed by theoccupant of the car or any of the switches 37, 38, 39 or 40 are opened,the current supply to the switch 27 is opened and the elevator isstopped.

When the switch 27 closes, its contact 27 also closes a circuit forrelay 30 as follows: From cathode 2' over left-hand contact 27 throughthe bridging piece thereof through coil 30 to line L. The relay 30 isthus energized as long as the switch 27 is energized. When relay 30 isenergized the contacts 30 are closed and contacts 30 are opened. Anegative potential is thus impressed upon plate 12 of the condenser 10in the manner aforedescribed in connection with Fig. 1, and if theswitch 27 opens and contacts 30 close, this negative potential isimpressed upon the grid circuit, thus making the grid negative withrespect to the cathode for a limitedtime and preventing the tube 1 fromconducting current. Therefore, if one of the push buttons 34, 35 or 36should be depressed at the moment when the elevator comes to a stop at afloor, current would not be supplied to the controlling mechanism for aninterval which permits the occupant of the car to open the door and stepout. The opening of the door, of course, opens the safety switchesaforedescribed and thereby eliminates the efiect of the depression ofany one of the push buttons until such switches are closed again by theclosure of the corresponding door.

The time delay is only eifective to cause a delay with respect to thelanding push buttons 34. 35 and 36 and is not eifective with respect tothe car push buttons 31, 32 and 33, because the latter push buttons arearranged to short circuit the condenser and its discharge resistance sothat no potential is impressed on the grid by the condenser in themanner aforedescribed.

If it is desired to have the elevator car move in the opposite directionto that described, a

corresponding push button is pressed and the switch 28 is energizedthereby reversing two of the motor connections and causing it toreverse, the operation of the various relays and contacts being the sameas that of the corresponding relays and contacts described for theascending operation of the elevator.

It is, of course, possible to use in addition to the interlocking andsafety device aforedescribed, such additional interlocking devices asare common with modern elevator installations but these form no part ofthe present invention.

It will be noted that in case of phase failure or phase reversal, thetube 1 is affected in the manner described in connection with Fig. 2 andthe aforementioned co-pending application and is under these conditionsincapable of supplying any current to the various magnet circuits, sothat no power is available for the operation of the controller and theelevator will therefore come to a stop and cannot be operated untilnormal conditions of phase rotation and phase continuity are restored.

What we claim as new and desire to secure by Letters Patent is:

1. In combination, a polyphase supply circuit,

a translating device, means responsive to variations in voltage, phaserotation and/or phase continuity of said supply, including an electrontube for establishing circuit connections between said supply circuitand said translating device, said tube having a control electrode, meansto interrupt the circuit of said tube to thereby stop discharge throughsaid tube and to reclose said circuit" for reviving said discharge bysaid tube and means rendered eiiective by current supplied by said tubeand acting on said control electrode to insure against discharge by saidtube for a given minimum period following cessation of discharge therebyupon interruption of said circuit.

2. In combination, a polyphase supply'circuit, a load circuit, a gaseouselectron tube provided with a cathode and anode connected between saidcircuits and with a control electrode, means to complete connection ofsaid circuits, means subjecting said electrode to a voltage which isderived from said supply circuit and which, under normal voltage andphase conditions in the latter circuit, lags a given angle behind thevoltage impressed on said anode, said tube being thereby caused todischarge at the beginning of the positive half cycle of impressedvoltage and the second mentioned means being sensitive to abnormalvoltage and/or phase conditions to reduce said lag, a condenser and adischarge impedance associated with said control electrode, means tocharge said condenser by a current passing through said tube to apotential capable of preventing starting of current flow through thetube for a given minimum period following cessation of discharge therebyupon interruption of current flow, means to discharge the condenserthrough said impedance upon such interruption and means to re-establishsaid connection at will.

3. In combination, a polyphase supply circuit, a load circuit, a gaseouselectron tube provided with a cathode and anode connected between saidcircuits and with a control electrode, means to complete connection ofsaid circuits, means subjecting said control electrode to a voltagewhich is derived from said supply circuit and which, under normalvoltage and phase conditions in the latter circuit, lags a given anglebehind the voltage impressed on said anode, said tube being therebycaused to discharge at the beginning of the positive half cycle ofimpressed voltage and the second mentioned means being sensitive toabnormal voltage and/or phase con ditions to reduce said lag, acondenser and a discharge impedance associated with said controlelectrode, means to charge said condenser by a current passing throughsaid tube to a potential capable of preventing starting of 'current flowthrough the tube for a given minimum period following cessation ofdischarge thereby upon interruption of current flow, means to dischargethe condenser through said impedance upon such interruption and means tore-establish said connection at will and simultaneously eliminate theeffect of said condenser upon said current flow.

4. In combination, a polyphase supply circuit, a translating device, agaseous electron tube provided with a cathode and anode connected tweensaid circuits, said tube being also provided with an electrode arrangedto control the current transmitted therethrough, said electrode beingconnected to the supply circuit to be normally subjected to a potentialwhich lags a given angle behind the anode potential, such lag beingreduced by abnormal current and/or voltage conditions in the circuit, acondenser and a discharge impedance associated with said controlelectrode, means to charge said condenser by a current passing throughsaid tube to a potential capable of preventing starting of current flowthrough the tube and means to interrupt the connection of said tube andto discharge the condenser through said impedance and to reestablishsaid connection at ,will.

5. In combination, a polyphase supply circuit, a translating device, agaseous electron tube provided with a cathode and anode connectedbetween said circuits, said tube being also provided with an electrodearranged to control the current transmitted therethrough, said electrodebeing connected to the supply circuit to be normally subjected to apotential which lags a given angle behind the anode potential, such lagbeing reduced by abnormal current and/or voltage conditions in thecircuit, a condenser and a discharge impedance associated with saidcontrol electrode, means to charge said condenser by a current passingthrough said tube to a potential capable of preventing starting ofcurrent flow through said tube and means to interrupt the connection ofsaid tube and to discharge the condenser through said impedance, thelast mentioned means being controllable to reestablish said connectionat will to revive the discharge of said tube subject to delay pendingdischarge of said condenser or alternatively to eliminate the delay dueto the charge of said condenser.

6. In combination, a polyphase supply circuit, a motor, reversing meansfor connecting said motor to said supply circuit, means for controllingsaid reversing means, said latter means being responsive to variationsin voltage, phase rotation and/or phase continuity of said supplycircuit and including an electron tube having a control electrode, meansto interrupt the circuit of said tube to thereby stop discharge throughsaid tube and to reclose said circuit for reviving discharge by saidtube and means rendered effective by current supplied by said tube andacting on said control electrode to insure against discharge by saidtube and restarting of the motor for a given minimum period followingcessation of discharge thereby upon interruption of said circuit.

7. In combination, a polyphase supply circuit, a motor, reversing meansfor connecting said motor to said supply circuit, means for controllingsaid reversing means, said latter means being responsive to variationsin voltage, phase rotation and/or phase continuity of said supplycircuit and including an electron tube having a control electrode, meansto interrupt the circuit of said tube to thereby stop discharge throughsaid tube and to reclose said circuit for reviving discharge by saidtube, means rendered effective by current supplied by said tube andacting on said control electrode to insure against discharge by saidtube and restarting of the motor for a given minimum period followingcessation of discharge thereby upon interruption of said circuit, andmeans to eliminate at will the time delay of said last mentioned means.

8. In combination, an elevator, a polyphase current supply circuit, amotor for driving said elevator, reversing means for connecting saidmotor to said supply circuit, means for controlling said reversingmeans, the second mennos-1,700

tioned means being responsive to variations in voltage, phase rotationand/or phase continuity or said supply circuit and including an electrontube having a control electrode, means to interrupt the circuit of saidtube to thereby stop discharge through said tube and to reclose saidcircuit for reviving discharge by said tube and means rendered effectiveby current supplied by said tube and acting on said control electrode toinsure against discharge by said tube and restarting of the motor for agiven minimum period following cessation of discharge thereby uponinterruption of said circuit.

9. In combination, an elevator, a polyphase current supply circuit, amotor for driving said elevator, reversing means for connecting themotor to said supply circuit, means for controlling said reversingmeans, the second mentioned means being responsive to variations involtage, phase rotation and/or phase continuity of said supply circuitand including an electron tube having a control electrode, means tointerrupt the circuit of said tube to thereby stop discharge throughsaid tube and to reclose said circuit for reviving discharge by saidtube, means rendered effective by current supplied by said tube andacting on said control electrode to insure against discharge by saidtubeand restarting of the motor for a given minimum period followingcessation of discharge thereby upon interruption of said circuit andmeans to eliminate at will the time delay oi! said last mentioned means.

10. In combination, an electron tube having a control electrode, acircuit supplied through said tube, means in series with said tube tointerrupt said circuit and thereby stop the discharge through said tubeand to reclose said circuit for reviving discharse by said tube andmeans rendered eflective by current supplied by said tube and acting onsaid control electrode of said tube to insure against discharge by saidtube for a given minimum period following cessation of discharge therebyupon interruption of said circuit.

11. In combination, a translating device, an electron tube in circuittherewith and having a control electrode, energy storage meansassociated with said tube, means to charge the former means by a currentpassing through said tube to a potential capable of preventing startingof current flow through said tube for-a given time after interruption ofsaid flow, and means in series with said tube to interrupt the circuitof said tube and to discharge said energy storage means and to reclosesaid circuit at will.

12. In combination, a translating device, a gaseous electron tube incircuit therewith and having a control electrode, a condenser and adischarge impedance associated with said tube, means to charge saidcondenser by a current passing through said tube to a potential capableof preventing starting of current flow through said tube for a giventime after interruption of said flow, and means to interrupt the circuitof said tube and to discharge the condenser through said impedance andto reclose said circuit at will.

13. In combination, a translating device, a gaseous electron tube incircuit therewith and having a control electrode, a condenser and adischarge impedance associated with said tube, means to charge saidcondenser by a current passing through said tube to a potential capableof preventing starting 0! current flow through said tube, means tointerrupt discharge of said tube and to discharge the condenser throughsaid impedance and means to revive said discharge of said tube subjectto delay pending discharge or said condenser or alternatively eliminatethe delay due to the charge of said condenser.

CARROLL STANSBURY. GLENDON C. BROWN.

